The instant invention relates to laser pointer devices, and more particularly to a laser pointer assembly having a thin profile laser head and housing structure.
Laser pointing devices are generally well known in the prior art. In this regard, the U.S. Patents to Lo U.S. Pat. No. 5,268,829; Jehn U.S. Pat. No. 5,307,253; Huang U.S. Pat. No. 5,335,150; Knowles U.S. Pat. No. 5,473,464; and Jehn U.S. Pat. No. 5,446,635 are representative of the current state of the art. As will be apparent from a review of the above-noted laser pointer devices, it is a common design feature that the laser pointer devices are packaged in cylindrical housings. The reason for this common feature is the fact that many commercially available laser diodes are pre-packaged in a cylindrical can assembly such as that generally indicated at 10 in FIG. 1. Referring to FIG. 1, the prior art laser head 10 include a cylindrical mounting head 12 having an integral heat sink 14, a laser diode 16 mounted on the heat sink 14, and a window 18 supported in front of the laser diode 16 by a protective housing 20, or "can" as commonly referred to in the art. The can 20 provides a protective enclosure around the laser diode 16 and the wire bond connection 22 to prevent physical harm to the laser diode 16 and wire bond 22 during manufacture and use. These types of laser heads also typically include a photodiode sensor 24 for monitoring light levels emitted from the laser diode. While these type of laser head assemblies 10 are highly effective and reliable, the physical characteristics of the cylindrical mounting head 12 limit the housing configurations to generally cylindrical constructions as shown in the above-noted patents, or alternatively to other housing structures having a minimum thickness which is limited by the outer diameter of the mounting head 12 plus the dimensions of any modular housing in which the laser head 10 is mounted. The laser head assemblies 10, which are typically referred to as transistor outline packages, are commercially sold in 2 standard sizes, namely 5.6 mm and 9 mm. Referring to FIG. 1A (prior art), a typical laser module of the prior art is illustrated and generally indicated at 26. The module assembly 26 comprises a laser head assembly 10, a mounting body 28, a collimating lens 30, and lens cap 32. Taking into account the smallest diameter of the transistor outline package 5.6 mm, and the necessary module housing in which it is mounted, a conventional laser module cannot be constructed any smaller than about 7.0 mm in diameter, or thickness. The laser module 26 is usually then mounted in another housing which in turn adds another 2-3 mm in diameter or thickness to the device, making the total diameter or thickness, no smaller than 9-10 mm. Accordingly, it is impossible to design a truly thin housing package from this type of laser head. As stated previously, while the existing laser head assemblies are highly effective, there is nevertheless a perceived industry need and consumer desire for laser mounting heads which have flatter packaging configurations than those currently available.
Accordingly, the instant invention provides a thin profile laser pointer assembly which incorporates a thin profile laser head, a simple constant voltage laser diode driver circuit, and a coin cell power source, all packaged into a thin profile housing which has a thickness of between about 2.0 and 6.0 mm.
The laser head comprises a thin, rectangular heat sink having parallel side edges, and further includes a laser diode mounted on a recessed shelf on a front edge of the heat sink. More specifically, the heat sink includes a recessed shelf at the inner end of an outwardly diverging slot formed in the front edge of the heat sink. The recessed shelf extends inwardly from the lower surface approximately half-way between the upper and lower surfaces of the heat sink, and the laser diode is mounted on the forward edge of the shelf. The wire bond from the laser diode passes through an aperture located next to the shelf to a contact pad on the upper surface of the heat sink body. The recessed shelf and slot protect the laser diode and wire bond from physical damage during handling and manufacturing thereof The housing comprises a thin rectangular body having a bottom wall and upwardly extending side walls. The rectangular heat sink is slidably received in an elongate rectangular mounting channel formed in a front portion of the housing. The mating parallel sides of the heat sink and mounting channel rigidly fix the laser diode in X and Z axes of a 90.degree. angle reference system while also permitting sliding linear movement of the laser diode along a "Y" axis, which defines the optical axis of the laser head assembly. The heat sink and mounting channel also positively fix rotation .theta..sub.x, .theta..sub.y, and .theta..sub.z of the laser diode around the X, Y and Z axes. A collimating lens is mounted at the front of the channel along the optical axis, and a projecting aperture is formed in the front wall of the housing in front of the lens for allowing the laser beam to exit through the front wall of the housing. The laser beam is focused through the lens by sliding the laser head assembly forwardly or rearwardly within the mounting channel to the proper longitudinal position. The laser head assembly is secured in focused position in the channel by an adhesive.
The battery is received in a circular recess formed in the rear portion of the housing. A hinged door is formed in the bottom wall of the housing for access to the battery after assembly.
The laser diode driver circuit and a switch are mounted on a two-sided circuit board which is received and secured over the open top of the shallow housing to form the top wall of the housing. Selectively placed contact pads on the circuit board engage corresponding electrical contact surfaces on the battery and laser head to complete the electrical circuit. The diode driver circuit utilizes a simple shunt voltage regulator which monitors laser voltage as the battery decays and adjusts current flow to provide constant voltage to the laser diode. More specifically, an operating circuit voltage is compared to the internal reference voltage of the shunt regulator. If the two values are the same, nothing happens. But, if the operating circuit voltage is higher than the reference, then the amplifier of the shunt regulator will draw more current from the battery reducing the overall voltage level to the diode.
A protective overlay sheet is mounted onto the upper surface of the circuit board to complete assembly of the laser pointer device. The overlay sheet protects and hides the electronic surface of the circuit board and can be provided with custom logo imprints for customized marketing of the laser pointer.
Accordingly, among the objects of the instant invention are: the provision of a laser pointer assembly having a thin profile housing with a thickness between about 2.0 mm and about 6.0 mm, and most preferably about 3.5 mm; the provision of a laser pointer assembly including a thin profile laser head; the provision of a laser pointer assembly wherein the thin profile laser head is slidably mounted in an elongate mounting channel; the provision of such a laser pointer assembly wherein the laser head and the mounting channel rigidly fix the laser diode in X and Z axes of a 90.degree. angle reference system, while also permitting linear sliding movement in the Y axis; the provision of such a laser pointer assembly wherein the laser head and mounting channel further fix rotation .theta..sub.x, .theta..sub.y, and .theta..sub.z of the laser diode around the X, Y, and Z axes; the provision of such a laser pointer assembly wherein a collimating lens is mounted at the forward end of the mounting channel and focusing of the laser beam is accomplished by sliding the laser head forward and backward within the mounting channel; the provision of thin profile laser head wherein the laser diode is mounted on a recessed shelf of a heat sink body to protect the laser diode and wire bond from harm during handling and manufacturing; the provision of a laser pointer assembly including a power regulator circuit which operates on constant voltage rather than constant current; the provision of a laser pointer assembly having a power regulator circuit which has no photodiode feedback loop; the provision of a laser pointer assembly having a power regulator circuit which uses a shunt-type voltage regulator; and the provision of a laser pointer assembly having a power regulator circuit with a shunt-type voltage regulator that uses the internal resistance of the battery to limit current to the shunt regulator.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.